1. Technical Field
This invention relates to liquid crystal displays (LCD's), and, more particularly to liquid crystal displays of the homeotropic and twisted nematic type having multi-domain cells.
2. Background Art
Flat panel displays have been become increasingly important in the computer industry and in other industries where the display of information is important. These types of displays provide unique opportunities for lowering the weight, size and eventually the cost of displaying information.
Liquid crystal displays seem to hold the most promise as the technology which will eventually be utilized in almost all practical flat panel displays. Considerable success has been achieved in small size color televisions and in monochrome flat panel displays as well as larger sizes used in color notebook or laptop computers. However, unlike the cathode ray tube display, which exhibits good viewing quality from a variety of angles, conventional liquid crystal displays suffer from a lose of contrast or contrast reversal when viewed from an angle other than normal to the plane of the display. This is due to the interaction of light with the molecules of the liquid crystal material in the liquid crystal display cells which make the flat panel display. Light traveling through these display cells at other than a normal angle of incidence interacts with the liquid crystal display molecules in a manner different from that of light traveling with normal incidence. The contrast between a light transmissive (white) state and a non-transmissive state (black) at other than the normal angle is drastically decreased, thus making such displays less desirable for use in many applications, such as flat panel television screens and large computer screens.
There have been various attempts to solve this problem. One method is discussed in U.S. Pat. No. 05,309,264, assigned to the assignee of the present invention, wherein a pattern of openings is formed in the common electrode. Such openings cause the display elements of the display to have more than one liquid crystal domain. This is a elegant approach; however, in order to provide sufficient optical performance, the width of such openings is required to be about twice that of the cell gap or larger. Importantly, for high density displays, the width of a given display element may be in the order of twice or triple the cell gap. In this case, this method becomes ineffective.